Alpha in Cycles isn't totally transparent, possible Mix node issue
Okay there you have the image going straight in to base color an image doesn't have transparency. You need to put it though a RGB to BW&gt;ColorRamp&gt; Fac in mix shader
As HoboFSlapfight had pointed out you could make these changes  &quot;But swapping out the Mix for an Add, and switching the mixRGB for a pair of Math nodes set to multiply (as pointed out by a friend earlier) also seems to have corrected the issue.&quot;
Transparent needs to be it's own shader.